I would contact the manufacturer. My new oven came with specific instructions re: do not use aluminum foil so they may have customer experience with this issue.
Yes call manufacturer, I was told never use foil in a self cleaning oven. If it's not gas, maybe pour a little hot water in bottom, let it sit awhile to try to loosen the food spill from foil. Good luck.
Here's a few tips Karen! Good Luck!
Soak it as long as you have to w/ soapy water, scraping what you can during the day til it's all gone. Also, instead, maybe spraying it w/ an oven cleaner and leaving it to 'soak' and scraping what you can til it's all gone.